Real Hubble Space


There are over 100 moons dancing around the eight major planets of our Sun's family. Most of them are small, frozen, icy objects, harboring only a relatively scanty amount of rocky material, that circle around the quartet of giant gaseous planets that dwell in the outer, frigid realm of our Solar System--far from the comforting warmth and brilliance of our Star. The quartet of majestic, giant denizens of our outer Solar System--Jupiter, Saturn, Uranus, and Neptune--are enveloped with gaseous atmospheres, and orbited by a multitude of dancing, sparkling moons and moonlets. In marked contrast, the inner region of our Solar System--where our Earth dwells--is almost bereft of moons. Of the quartet of relatively petite, rocky "terrestrial" planets--Mercury, Venus, Earth, and Mars--only Earth is circled by a large Moon. Mercury and Venus are moonless, and Mars is orbited by a duo of tiny, lumpy, potato-shaped moons, Phobos and Deimos. Phobos and Deimos are probably escaped asteroids, born in the Main Asteroid Belt between Mars and Jupiter, that were captured by the gravitational embrace of the Red Planet long ago. In addition, the newly collected data derived from the GRAIL mission helps astronomers redefine the late heavy bombardment--a proposed episode that occurred about 4 billion years ago, during which a heavy shower of projectiles pelted the bodies of the inner Solar System, including Earth and its beloved Moon, creating heavy lunar cratering in the process. The concept of the late heavy bombardment is primarily based on the ages of massive near-side craters that are either within, or adjacent to, dark, lava-flooded basins (lunar maria), that are named Oceanus Procellarum and Mare Imbrium. However, the composition of the material existing on and below the surface of the lunar near-side indicates that the temperatures beneath this area are not representative of Earth's Moon as a whole at the time of the late heavy bombardment. The difference in the temperature profiles may have caused scientists to overestimate the amount of crater-excavating projectiles that characterized the late heavy bombardment. New studies by GRAIL scientists indicate that the size distribution of impact craters on the lunar far-side is a more accurate reflection of the crater-forming history of the inner Solar System than those pock-marking the near-side. We earthlings love to look up at the moon. So much does the moon enamor us; we write movies, songs and poems by the droves that contain the name of the earth's super satellite. A case in point is the fact that one of the biggest selling record albums of all time is Pink Floyd's "Dark Side of the Moon."